Method of undulating rods for electrode structures



1957 'R. ZAPHIROPOULOS 2,773,161

METHOD OF UNDULATING RODS FOR ELECT RODE STRUCTURES Filed Sept. 15, 19532 Sheets-Sheet l 1957 R. ZAPHIROPOULOS 2,778,161

METHOD OF UNDULATING RODS FOR ELECTRODE STRUCTURES Filed Sept. 15, 19532 Sheets-Sheet 2 United States Patent METHOD OF UNDULATING RODS FORELECTRODE STRUCTURES Application September 15, 1953, Serial No. 380,2056 Claims. (Cl. 49-81) The present invention relates to the undulation ofelongated rods through the application of force or pressure effective atgenerally uniformly spaced positions therealong with successivepositions of pressure application being from opposite directions. Therods may be of any desired cross-section but for convenience may beconsidered as generally circular. The appliedpressure is normally of amagnitude insufiicient to deform the rod until it is softened orplasticized, which softening then permits it to assume a generallyzigzag configuration, with the distortion being generally proportionalto the pressure applied. The distorted shape is preserved while the rodis hardened.

Undulated rods in accordance with the foregoing find application asvibrational damping rods in grid structures employing substantiallyparallelly arranged tautly strung conductors generally occupying acommon plane. One or more undulated rods having insulatingcharacteristics may be interwoven in such grid structures to dampvibrations occasioned by the physical properties of the grid or arisingfrom the effects of electrical stresses established when the gridstructure forms an operative component of an electron tube.

The invention has particular application to a multiple strand gridstructure for location in proximate relation to a target or screen areaof a cathode-ray tube. The application of suitable potential to the gridand target structures relative to the electron beam source of thecathode-ray tube establishes an electric focusing field between the gridstructure and target. area. If the cathode-ray tube is to be used forthe reproduction of color television, the target or screen area thereofis provided with light producing phosphor coatings of differentcharacteristics arranged thereon in cyclically repeating sequence sothat light observable in selected different colors obtains from beamimpact on the target. Control .of the electric field enables the angleof incidence of the scanning beam to be altered while the beam isfocused to substantially subpunctiform size in at least one dimension atthe position of impact upon the target area. 1

The individual strands of the grid structure are tensioned to maintainsubstantialparalleelism while occupying substantially coplanar relation.The potential applied to the target relative to the electron beam sourcemay be approximately 3 or 4 times that applied to the grid. Then byestablishing a difierence of potential approximately equalling ,4; ofthat normally on the grid, between adjacent strands of the grid, theangle of incidence of the trace is altered and the beam is deflected inthe direction of the strands which are most positive relative to thebeam source. By making the spacing between adjacent strandssubstantially equal to the Width of a single color cycle, the beam maybe caused to impact the phosphor coated target at any desired positionthereby effecting color reproduction.

Often times, as many as 400 to 500 or more strands may comprise a singleelectrode structure usable to effect color reproduction. The tautlydrawn individual,

strands of such an electrode structure have a natural period ofvibration, the effects of which adversely modify the functions of theelectrode structure as above outlined. Any vibration established amongthe strands varies the spacing between the normal plane of the electrodestructure and the target electrode, thereby causing thediflierence inpotential established between the electrode structure and the target tobe effective over different spacings which disturbs the beam focus.Likewise, the fact plied thereto different potentials with respect tothe electron beam source tends to establish vibration in themulti-strand electrode structure particularly troublesome when it isappreciated that the frequency of changing the respective potentialsapplied to adjacent strands is high. Y The present invention provides amethod of undulating rods which are respectively interleaved among thestrands of the grid structure. The undulation permits alinement of thegrid conductors in a common plane and serves to maintain thedamp rods insuitable orientation therewith. The damp rods are of a diameter or widthsufiiciently small as to preclude the casting of shadows on the viewingor target area of the cathde-ray tube. Also, the damp rods generallypossess insulating characteristics since they contact adjacent strandsof the electrode structure which in certain applications have differentpotentials applied theretorelative to the beam source as abovementioned. Vitreous rods having a diameter in the neighborhood of from 3to 6 mils have been found suitable for use as the damp rods hereindescribed, since they are thermo plastic, inert under electronbombardment, and good insulators. The invention also contemplates theformation of strip-like elongated members, such as, glass ribbon intovibrational damping elements.

The vitreous rods are first interleaved in the grid structure such thatadjacent strands exert pressure from opposite directions against thevitreous rods and at spaced positions therealong. The interleaving isconveniently accomplished if a'spreader bar is first placed through thegrid such that adjacent strands are displaced oppositely to provide freepassage for a vitreous rod which is then inserted along an edge of thespreader bar and normal to the strands of the grid. The spreader bar isthen removed to permit the strands of the grid to exert pressure againstthe viterous rod of a magnitude normally thereof by the grid strands inassuming substantially coplanar relation. Upon cooling the damping rodretains its zigzag shape and the structure is ready for mounting in theviewing end of a cathode-ray tube.

Suitable apparatus for carrying out the method outlined may comprise anopen frame adapted to support the grid and clamped rod. Preferably, theopen frame includes at least a pair of cross-members adapted to supportthe grid structure with the rod occupying a position parallel with andsubstantially midway between the cross-members such that the strandsassume substantially coplanar relation where supported. A guidewayspanning the open frame is provided for a traveling heater which isadapted for proximate location with a clamped rod. Means are providedfor moving the heater along the guideway at a controlled rate so thatthe rod is softened by heat from the traveling heater and undulated bythe strands in returning to a common plane. If more than a singlevibrational damping rod is to be employed in an electrode structure asdescribed, the guideway and traveling heater are merely moved along theframe to a position to operate upon a further vibrational damping rod inthe manner aforestated. In the alternative, a multithat adjacent strandsmay have ap-.

- anchoring wire looped filament heater or a plurality of guideways andassociated traveling heaters may be-employed simultaneously to effectthe undulation of a plurality of clamped vibrational damping rods.However, in the latter event the heaters are staggered so that a singleconductor of the electrode structure is not heated in many spots atonce, thereby avoiding sagging. In'lieu oi the traveling heater, one ormore stationary filaments extending across the open frarne may beutilized for heating the clamped vitreous rods. Such a heatingarrangement is shown and described in United States application SerialNo. 380,311 entitled Method of and Apparatus for Undulating Rodsconcurrently filed by the same inventor.

With the foregoing in mind, amongthe objects of the present invention,are the following: The provision of a simple method of undulating rodsand the provision of apgaratus-of simple character'for undulating aclamped 1"0 Other and further objects of the present invention willbecome apparent to those skilled in the'art from a reading of thefollowing detailed description thereof when taken in the light'of theaccompanying drawing wherein:

Fig. 1 is an isometric view of apparatus in accordance with the presentinvention suitable for effecting the undulation of a vitreous rod;

Fig. 2 is a view in elevation of a target and electrode structure with aspreader bar inserted between the electrode-strands to permit theinsertion of a vitreous rod to be undulated;

Fig. 3 is an enlarged isometric view of a portion of the assembly ofFig. 2;

Fig. 4 is an enlarged sectional view of a. portion of the structure inaccordance with Figs. 1 and 2 and including-a traveling heater inoperative relation therewith;

Fig. 5 is an isometric view of a portion of the traveling heater; and

"Fig. 6 is a view partly in section and partly in elevation of thetraveling heater and associated guideway structure in operative relationwith a rod being undulated.

In Fig. 1 there is shownan open table-like frame 11 having a pair ofhorizontal supporting bars 13 fixed thereacross. The bars 13 areprovided to support a target and electrode structure as illustrated inFig. 2. The structure is shown in elevation as it would appear whenviewed from the electron beam source of a cathode-ray tube. Atranslucent base 15 has affixetl thereto, near outer edges thereof, apair of glass spacer bars 17 suitably notched (not shown) to accommodatethe conducting strands 19 of the grid which occupy a common planebetween the spacer bars. As was mentioned, alternate strands 19 maycomprise a set of grid wires with the intermediate strands 19 forming asecond set of grid wires.

Fig. 3 shows the grid wire anchoring structure capable of permittingelectrically separate sets of conductors to comprise the grid structureof Fig. 2. A rectangular frame 21 is placed against the face of the base15 opposed to the face adapted to be impacted by the electron scanningbeam. A pair of anchoring bars 23 (only one of which is shown in Fig. 3)is affixed respectively to pposite arms of the rectangular frame 21.Each of the anchoring bars 23 is provided with spaced apart hooks Zwhichmay comprise bent tabs disposed along an edge of the bar over whicha continuous conductor is looped back and forth to provide a first setof parallelly located conducting wires for the grid. A layer ofinsulation 27 electrically separates a second rectangular frame member29 from the first set of grid wires. A second pair of bars 31 is securedto opposite arms of the second frame 29 and have books or turned outtabs 33 disposed at spaced intervals respectively between the hooks ortabs 25 to accommodate a second conducting at intervals over the hooks33 to form the second set of grid wires. The structure of Figs. 2 and 3permits the application of difierent potentials relative to the beamsource to the anchoring bars 23 and 31.

The phosphor target area is located within the dotted all) outline ofthe frame 21 on the face of the base 15 visible in Fig. 2. Generally thephosphor coatings are covered by a thin aluminum film or other materialwhich is electron permeable and electrically conducting so that asubstantially uniform potential surface is available on the face of thebase 15. A difierence of potential is established between the gridstructure represented by the strands 19 and the aluminum film deployedonthe base 15. As hereinbetore mentioned through the application ofsuitable potential, the grid strands provide the effect of electronlenses capable of focusing'the scanning beam. on the phosphor coatings.The application oi-ditr'erent potentials to adjacent strands 19'enablesdefiection of the focused beam. However, a diiterence of.potential existing between adjacent strands 19 tends to establishvibration among the strands'which affects the deflecting function.Likewise, changing of the instantaneous potential effective at the gridrelative to that of the aluminum film introduces electrical forces ofattraction and repulsion which tend to move the strands 19longitudinally of the cathode-ray tube. Such displacement is undesirablein that beam focus is noticeably affected. Also, vibration isestablished among the strands 19 due to the physical properties'oftheplurality of tautly drawn conductors.

A vitreous rod having a portion thereof undulat ed in theform'of aclamping rod is represented at 37 in Fig; 6. The rod 37 is'showninterleaved between adjacent strands 19 of the grid strnctureof Fig. 4.A fiat spacer bar 39 is first inserted into the grid structure ininterleaved fashion with respective strands 19 as is shown in Fig. 2.Adjacent strands are displaced in opposite directions from the normal orcommon plane of the grid structure 'by the spacer bar. The rod 37 isthen passed freely in interleavedfashion through the grid structureadjacent to an edge of the spacer bar 39. The spacer bar 39 is thenwithdrawn'so that adjacent strands 19 exert pressure fromoppositedirections and at spaced intervals along the rod 37. With therod to be undulated in this position, the assembly of Fig. 2 is placedon the cross bars 13 of the frame 11 such that the rod 37 occupies aposition substantially midway between the bars 13 and paralleltherewith. As is best represented in the cross-sectional view of Fig. 4,the strands 19 occupy substantially coplanar relation where supported bythe bars 13 but are displaced in opposite directions intermediate thebars by the rod 37.

The rod 37-is softened by heat generated by a travelling heater whichcomprises a ceramic holder 41 adapted to contain .a heating filament orcoil 43 (Figs. 5 and 6). Electrical leads 45 comprise supporting legsfor the holder 41. The leads pass through a horizontal block or carriage47 adapted to slide along a slot 49 provided in a box-like support 51hinged to a cover plate 53. The cover plate 53 is secured to a trolley55 adapted to move along a cross arm 57 of the openframe 11. A screw 59is provided to lock the trolley 55 in position along the cross arm 57 byengaging any of a plurality of holes 61 provided therein. A spring catch63 depends from the trolley 55 for engagement with the groove 65 to lockthe box-like support 51 in operative position with the ceramic holder 41extending through an opening 67 in the cover plate 53. In this mannerthefilament 43'is placed adjacent to the clamped rod 37 as is shown inFigs. 4 and 6.

By means of pulleys 71 (Fig. 6) and 73 (Fig. 1), the latter ofwhich isdriven by a motor'75, the block 47 supporting the travelling filament iscaused to move along the slot 49 at a constant or controlled rate. Themotor 75 is supplied with electrical power through a cord 77 andelectrical plug 79. Electrical connection is established to the filament43 through a pair of inlet leads 81 preferably including an adjustablerheostat 83 between the inlet plug 85 and the heavy leads 45. Byadjusting the rheostat 83 the amount of current supplied controlledproviding a direct released to drop the travelling heater and box-likesupport 51 to the position shown in Fig. 1 so that the trolley 55 may bemoved along the cross arm 57 to aline the opening 67 in the cover lid 53with a second rod to be undulated. The box-like support 51 is thenraised to permit the spring catch 63 to engage the notch 65 and lock thetravelling heater in position to heat the second rod. Generally, aplurality of the cross bars 13 is provided so that each damp rod to beformed is disposed between a pair of such cross arms. The number of damprods to be employed in a grid structure depends upon the over-all sizeof the grid structure and the diameter of the strands 19. Three suchdamp rods will usually sulfice in an average size grid structure.

While the grid strands 19 have been referred to as substantiallyuniformly spaced, it is to be understood that the spacing may hegraduated to compensate for deviations in the angle of incidence of theelectron scanning beam between the axis and the edges of the targetarea.

What is claimed is:

l. The method of forming a grid of substantially taut ands disposed in acommon plane to undulate an rod which comprises the steps of displacingadjacent strands in opposite directions from the common plane, insertingthe elongated rod between the dis placed strands, applying pressureagainst the rod from opposite directions through adjacent strands,progressive- 1y applying heat at local regions to the rod to reduce itat heated regions to a softened state so that undulation occurs as thetaut displaced strands return to the common plane, and thereuponprogressively discontinuing the heating at the local regions so that therod will harden in the undulated shape.

2. The method of fabricating a grid of taut strands stressed in a commonplane to undulate an elongated vitreous rod which comprises the steps ofdisplacing adjacent strands in opposite directions from the commonplane, inserting said rod between the displaced strands subjecting theelongated rod to pressure applied from opposite directions throughadjacent strands, heating the rod to soften it at the successo that rodundulation occurs as lowing softening so that rod hardening occurs withthe undulated shape preserved.

3. The method of constructing a vibrationally damped grid for focusingbeams of electrons on the target of a cathode-ray tube which comprisesthe steps of constructing a grid of tautly stretched substantiallyparallel and coplanar wires, elastically displacing said wires fromtheir coplanar relationship and inserting a substantially straightthermoplastic insulating rod between the displaced wires to interweavesaid rod therewith, applying heat to only the portion of said gridincluding said rod until the rod becomes sufliciently plastic to deformand permit the wires to return to their coplanar relationship, andthereupon discontinuing the application of heat to permit hardening ofthe rod in its deformed state.

4. The method of constructing a vibrationally damped grid for focusingbeams of electrons on the target of a cathode-ray tube which comprisesthe steps of constructing a grid of tautly stretched substantiallyparallel and coplanar wires, elastically displacing said wires fromtheir coplanar relationship and inserting a substantially straightthermoplastic insulating rod between the displaced wires to interweavesaid rod therewith, applying heat from a concentrated source to said rodand moving said source relatively along said rod at a rate such as torender said rod sufiiciently plastic where the heat is applied to deformand permit the wires to return to their coplanar relationship andimmediately thereafter harden as the source passes.

5. The method of vibrationally damping a cathode-ray tube color-controlgrid structure formed of a multiplicity of substantially parallellypositioned linear conductors normally held in tension in substantiallycoplanar relationship while strung across the window area of a frame theinner dimensions of which encompass and bound the tube raster to bescanned, which comprises the steps of interweaving a vitreous rodthrough the stretched linear conductors in a direction generallytransverse thereof so that the conductors are displaced relative totheir normal plane with substantially one-half of the conductors movedto one side of the normal plane and one-half moved to the other side ofthe normal plane, the maximum conductor displacement at each side of thenormal plane being at the contact point between the vitreous rod and theconductor and being for a distance corresponding to one-half thetransverse dimension of the vitreous rod plus one-half the conductordiameter so that the tensioned and displaced conductors tightly hold therod, applying heat to the rod at localized regions along its length,progressively moving and shifting the region of heat application alongthe rod length, and limiting the heat application period at each regionto a time only sufficient to render the heated rod portion plasticthereby to permit the tensioned linear conductors progressively toreturn to their normally c0- planar position and thereby progressivelyundulate the rod at heated regions along its length after which the rodimmediately hardens in its undulated state due to heat removal and istightly held by the conductors with which it is interwoven.

6. The method of vibrationally damping a cathode-ray tube color-controlgrid structure formed of a multiplicity of substantially parallellypositioned linear conductors normally held in tension in substantiallycoplanar relationship while strung across the window area of a frame theinner dimensions of which encompass and bound the tube raster to bescanned, which comprises the steps of interweaving a vitreous rodbetween the stretched linear conductors in a direction generallytransverse thereof so that adjacent conductors are displaced in oppositedirections relative to their normal coplanar relationship against thetensioning force exerted thereon with the maximum conductor displacementfrom normal coplanar state being at the contact point between thevitreous rod so that the tensioned displaced conductors tightly hold therod, applying heat to the red at localized regions along its length,progressively moving and shifting the region of heat application alongthe rod length, limiting the heat application period at each region to atime only suificient to render the heated rod portion plastic thereby topermit the tensioned linear conductors progressively and sequentially toreturn to their normally coplanar position and thereby progressivelyundulate the rod along its length immediately following heating afterwhich the rod hardens in its undulated state due to heat removal and isheld in relatively tight contact with the tensioned conductors.

References Cited in the file of this patent UNITED STATES PATENTS2,121,939 Williams June 28, 1938 2,239,546 Black et al Apr. 22, 19412,310,537 Morrison Feb. 9, 1943

